1. Field of the Invention
The present invention relates to a gas/liquid separation device. More particularly, the invention relates to a gas/liquid separation device applicable to a crankcase emission control system. The device separates oil mist from blowby gas of an internal combustion engine and recirculates it to an oil collection chamber.
2. Description of the Related Art
A crankcase emission control system for introducing blowby gas from a crank chamber, or a head cover of a cylinder head in communication with the crank chamber, into an air induction passage are known in the art (for example, see Japanese Unexamined Patent Publication (Kokai) No. 59-208116). It is also known in the art to provide an oil trap in a blowby gas recirculation passage for trapping an oil mist carried by the blowby gas, and separate them from each other (for example, see Japanese Unexamined Patent Publication No. 59-206610).
When the blowby gas is treated simply by a recirculation thereof into the air induction passage, the oil mist carried by the blowby gas is also introduced into the air induction passage. This increases the consumption of engine lubrication oil. Also, the oil or decomposition products thereof may adhere to the inner peripheral wall of the air induction system. In the worst case, the oil and/or decomposition products may accumulate on the inner periphery of the air induction passage and cause various problems. Therefore, there is a need for separating the oil mist from the blowby gas to be introduced into the air induction passage, and for returning the oil to the lubricant collector.
The oil mist can be collected or recovered by various means, such as an oil trap with a baffle plate. However, it is difficult to return the collected oil to the crank chamber or the head cover through the same piping, against the flow of the blowby gas, unless the piping is large. Therefore, in the prior art, the collected oil is held in an oil strainer while the engine is running. It is returned to the oil collection chamber in the crank chamber under the force of gravity when the engine is not running.
Accordingly, when the engine is driven for a long period, the amount of oil adhered to the oil strainer is increased to the point of saturation. Once the oil strainer is saturated, a balance is established between the amount of oil mist to be collected and the amount of oil again atomized by the flow of the blowby gas. Therefore, it becomes impossible to further collect the oil mist.